S-meter readings when using an Airspy HF+


Patrick
 

Hi there,

Last night, I made a recording on MW, using a my HF+ with its default settings (HF AGC ON, HF Threshold LOW, HF Preamp unticked) and SDR# latest version / firmware. Antenna is a Wellbrook ALA1530LN mounted outdoors.

Listening to the files right now on v3 (to run your amazing Data File Analyser), I notice the S-meter readings are very high and seem "overrated".
AM mode, 4 kHz filter reads -60 dBm on a "clear" frequency, and about -20 dBm on powerful stations.
Using AGC OFF with Gain set 0 dB even causes distorision.

When recording from an ELAD S2, the loudest stations read about -50 dBm. Similar values if recording with an RSPduo and playing back with SDRuno software.
That's about 30dB discrepancy.

Should I modify some settings on my HF+ before recording ?
What does explain such a hugh difference between both SDRs ?

(note :  a couple of months ago, I recorded from v3 but then it was impossible to use the file with SDR#, I mean the waterfall was totally saturated, no way to see a single signal even with contrast at its lowest).

Thanks for tips / suggestions

BR.


paul newcombe <G6YZC@...>
 

BR,

I love SDRC but think it should come with a bottle of Typex (White out) and the first thing you should do is cover up the S meter. 

When ever most people I have spoken with try to use SDRC and an SDR they immediately add as much attenuation in front of it as needed in order to make the S Meter read the same as their big 3 brick rig. The next thing they do is complain that the SDR is deaf and totally useless. 

I know on 2m EME my SDRC S meter reads somewhere around -71 dBm (off the top of my head) and I also know with a -71dBm noise floor you cannot do EME. So I just ignore the meter and continue to work stations off the moon.

Paul N2EME


From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> on behalf of Patrick <aunumero73@...>
Sent: Wednesday, September 26, 2018 7:57 AM
To: main@sdr-radio.groups.io
Subject: [SDR-Radio] S-meter readings when using an Airspy HF+
 
Hi there,

Last night, I made a recording on MW, using a my HF+ with its default settings (HF AGC ON, HF Threshold LOW, HF Preamp unticked) and SDR# latest version / firmware. Antenna is a Wellbrook ALA1530LN mounted outdoors.

Listening to the files right now on v3 (to run your amazing Data File Analyser), I notice the S-meter readings are very high and seem "overrated".
AM mode, 4 kHz filter reads -60 dBm on a "clear" frequency, and about -20 dBm on powerful stations.
Using AGC OFF with Gain set 0 dB even causes distorision.

When recording from an ELAD S2, the loudest stations read about -50 dBm. Similar values if recording with an RSPduo and playing back with SDRuno software.
That's about 30dB discrepancy.

Should I modify some settings on my HF+ before recording ?
What does explain such a hugh difference between both SDRs ?

(note :  a couple of months ago, I recorded from v3 but then it was impossible to use the file with SDR#, I mean the waterfall was totally saturated, no way to see a single signal even with contrast at its lowest).

Thanks for tips / suggestions

BR.


Patrick
 

EDIT : of course, when I wrote : " Should I modify some settings on my HF+ before recording ?" I was refering to the setting from SDR# "source" window (HF AGC, HF treshold, HF preamp, HF att)

Le mer. 26 sept. 2018 à 13:57, Patrick <aunumero73@...> a écrit :
Hi there,

Last night, I made a recording on MW, using a my HF+ with its default settings (HF AGC ON, HF Threshold LOW, HF Preamp unticked) and SDR# latest version / firmware. Antenna is a Wellbrook ALA1530LN mounted outdoors.

Listening to the files right now on v3 (to run your amazing Data File Analyser), I notice the S-meter readings are very high and seem "overrated".
AM mode, 4 kHz filter reads -60 dBm on a "clear" frequency, and about -20 dBm on powerful stations.
Using AGC OFF with Gain set 0 dB even causes distorision.

When recording from an ELAD S2, the loudest stations read about -50 dBm. Similar values if recording with an RSPduo and playing back with SDRuno software.
That's about 30dB discrepancy.

Should I modify some settings on my HF+ before recording ?
What does explain such a hugh difference between both SDRs ?

(note :  a couple of months ago, I recorded from v3 but then it was impossible to use the file with SDR#, I mean the waterfall was totally saturated, no way to see a single signal even with contrast at its lowest).

Thanks for tips / suggestions

BR.


Bjarne Mjelde
 

Be aware that the standard signal level readings in SDR# is not dBm but dBFS.
--
Bjarne Mjelde
arcticdx.blogspot.com
Remote rx: kongsdr.proxy.kiwisdr.com:8073/